Preparation of catalyst containing silica and alumina or magnesia or both



Patented Apr. 15, 1952 PREPARATION OF CATALYST "CONTAINING SILICA AND ALUMIN'A'fORLMAGNESIA "OR James I P. zWest; Westmont,:.lll., *assignor to Universal Oil Products Company, @Chicagor 111,, a corporation oiflDelaware NoDrawi-ng. Application September 29, 1948, rSerial No.5l ,844

'1 81'Claims. (Cl.- 252- 453) i'llhisinvention. relates to the .preparationaof 1' catalytically :active' composites containing 1 silica, iza'lumina, wand/or magnesia which i. are ;,=par:ticularlyuseful in catalyzing hydrocarbon-cracking rreactions; especially forthe production of gasoline utilizing high-boiling petroleum fractions as :charging stocks. Moret specifically, the invention vconcerns catalytically= active metal oxide 1 com- ;jpositestcomprisingl silica and at: least one com- ;ponent selected r from the group tconsisting of aalumina and imagnesia which are prepared by a metathasis-type .of ireaction i between &an :alkyl orthoesilicateand an-organic tacid .salt. of aluwmi-num and/orwmagnesium formed :at selected 5 reaction. conditions.

a-SiJica-base catalysts containing calumina stand/or magnesia in intimate [association there- --withhave been-widely-known andutilized' by the 3 DliOliflIt as :catalystsforeflecting specific-v hyxdrocarbon conversion reactions, 7, such as the tcracking of-vhigh molecular weight petroleum hycdrocarbons I for the production "of :motor 5 fuel 1 gasolines therefrom. Thesecatalysts which have *tbeen --invariably prepared by impregnating. a silica -sol particle with v the salt of aluminum f :and/or magnesium,- and .then subsequently consverting thealuuminum'and/or magnesium. salt to ---the corresponding .oxides, are characterized. generallyl by their; high. ldensity as compared. to the eatalystcf theflpresent invention-and a relatively low, porosity, again i on the 7. basis of comparison l with the, present .catalyst 1 composites. The use -01. catalysts having low densities an'dihigh porovasities accompaniedlby high activities has become increasingly important since the advent, of 'jfluidsized "processes in l the treatment of petroleum Liractions, such. as Ifiuid-ized cracking. processes.

High porosity and low. density are, particularly ;,ad yantageous ,qualitiesiin a catalyst vvhenfgit is toabe utilizedlinl'flnidized processes because of eease of maintaininglthe. catalyst in suspension smaithe reactant. vapors .during' the reaction and rithelhigh con'ver'sionofi charging stocks, resulting ither'eby. i;.'I!he.. silica-base catalysts, prepared by iithe proces eof 'thespresent invention are charstacterizdlebyttheirl low "density as well as high vi p orosity..and their. relatively high degree, of ac- 'tiv'ityin catalyticl cracking. reactions. llTheji-presentvcatalystisl therefore especially recommended :Ior f'fiuidized processes wherein T'the aforesaid ,;;physical-: -proper.tiesl are especially. advantageous.

aOne/objecttofhthe present. invention is .to pregwpareua: catalyst. composite containing silica alucminaeand/or magnesia-which :is. particularlyv active in; promoting hydrocarbon cracking reacr tions;especially insfiuidized processes t this i type.

vAnotherpobjectrof this invention is to -provide improved :silica-base catalysts containing alumina (and/Ora magnesia free of foreign impurities' -which tendto 1' reduce the catalytic activity .qand life oft-he composite.

"IIIFOHBn-Of its embodiments the present invention relates to -a process for the preparationof a ;hydrocarbon cracking catalyst consisting of a composite ofthe-oxides of silicon and at least one oxide ofza-metalselected Iromthe, group consistingof alumina and magnesia which comprises reactingizan alkyllortho-silicate with at least one vmetal..-acid salt-selected from the group consistri-ng ofta monobasic aluminum acid salt and a magnesium di-acidsalt for a-time temperature,

and pressure-sufficient to form said catalyst com- ;=posite substantially free of organic material.

Another-embodiment of the invention relates -to.-a process for. the production of acatalyst comgoaprising acomposite of silicawand alumina by reacting a basic aluminum acid salt ofzanorganic acid with an alkyl ortho-silicate at a temperature of from about 150 to about 300 0., and at a pressure sufilcient to maintain at least partial liquid phase, thereafter releasing the ambient "pressure and recovering fromtheresidue, said ..composite of silica and alumina.

nstill another catalyst which maybe. prepared L-bymeans of, the present procedure is a silica-base magnesia catalystformed. by the process which comprisesfreacting ethyl ortho-silicate and maganesiumidiacetateata temperature of from about 150. .to about 300C. and at a pressure sufiicient towmaintain at' least a portion of thev reactants :in substantially liquid phase, up to about l00'at- :mospheres, and thereafter recovering a compositeof magnesiumand silicon oxides fromthereuaction mixture. l 7

- Other objects and.specific embodiments. oithe 40. presenttinventionvwill be hereinafter rferredlto in greater detail in a the following further .I'de- -scription of the invention.

The catalyst composites vof thepresentiinventioncontianing silica as a component common to all -ofsaid composite catalysts, .are prepared by means "ofua-t metathesis-type of reactionlbe- :tween an' alkyl ortho-silicate as one i of the, reacting components-and .an organic acidcsalt iof magnesium and/orsaluminum, preferablyca l cart boxylic acid" salt of. the lower fatty acidseries.

The. alkyl-orthorsilicate reactant is preferably selected from the alcohol estersuot silicicacid containing at least two and not more than five u carbon atoms per molecule, such as ethyl l orthosilicate,- propyl ortho-silicate, etc., including amyl -orthoesilicate. These latter .silicic .acid .esters are preferred because of the desirability of maintaining substantially liquid phase during the course of the metathasis reaction and the ability of maintaining said esters in liquid phase a the reaction conditions herein specified. Further preference is accorded ethyl ortho-silicate not only because of the relative ease of maintain ing the same in liquid phase at the reaction temperatures herein specified, but, further, because of its relative cheapness and general availability.

The reactant referred to herein as a metal acid salt selected from at least one metal of the group consisting of aluminum and magnesium are preferably the corresponding salts of a mono-carboxylic acid selected from the members of the fatty acid series. The monobasic aluminum acid salts are prepared, for example, by reacting aluminum oxide, such as an alumina ore containing gamma-alumina, with an organic acid at a temperature sufiicient to form the monobasic aluminum acid salt. For this purpose, impure oxide ores, such as the natural trihydrates or the mixed hydrates and anhydrides'may be reacted with the acid and the salts formed thereby removed from the reaction product. The corresponding magnesium acid salts are similarly prepared by reacting magnesia or precipitated magnesium hydroxide with the acid at suitable reaction conditions tofoi'mthe monoor di-acid salts. Suitable organic acids utilizable to form the aluminum and magnesium acid salts include acetic acid, and formic acid which are preferred herein, tri-chloroacetic acid, dichloroacetic acid,

1 mono-chloroacetic acid, oxalic acid, malonic acid.

succinic acid, tartaric acid, benzoic acid, and others. In the case of aluminum, the reaction of an alumina ore such as aluminum oxide tri-- hydrate is represented in the following equation where acetic acid represents a typical organic acid reactant.

' The product is a mono-basic aluminum acetate salt comprisingone of the preferred reactants involved in the present process for the preparation of a silica-base alumina catalyst In the case of the reaction of magnesia with an acid of the above series, the di-acid salt of magnesium is formed in the presence of an excess of the acid reactant which is capable of reacting with ethyl- 'ortho-silicateto form the silica-magnesia catalyst of thepresent invention. A mono-carboxylic thasis reaction to form a catalyst composite containing a mixture of magnesium and aluminum oxides composited with the silica component. The magnesium and aluminum acid salts are gen- "erally prepared by reacting the oxide ores with "the particular acid desired at a temperature above about 150 0., preferably from about 180 "to about 250C. in the presence of an excess of the acid, generally from about 6 to 1, to about 12 to 1 molar proportions of the acid to the metal oxide ore.

The reaction of an alkyl ortho-silicate' with an organic acid salt of magnesium and/or aluminum to form a catalytically active composite con- 4 taining silica, magnesia, and/ or alumina, depending upon whether an acid salt of magnesium or aluminum individually or a mixture of the two acid salts is employed in the metathasis reaction, is effected at temperatures within the range of from about 150 to temperatures below the normal decomposition point of the metal salt,

generally about 300 C., and preferably at temperatures of from about 200 to about 250 C. The reaction mixture is preferably maintained under pressure sufiiciently high to provide substantially liquid'phase conditions within the reaction mixture, generally up to about 100 atmospheres. Such pressures may be obtained in the reaction mixture by charging an inert gas, such as nitrogen, carbon monoxide, etc., into the reactor at the desired pressure prior to heating the mixture to reaction temperature. The proportion of the respective reactants utilized in the metathasis reaction, that is, the alkyl orthosilicate and organic acid metal salt or salts, is

dependent upon the ultimate compositiondesired in the final catalyst. Desirable and highlyeffective hydrocarbon cracking catalyst usually-containfrom about 0.1 to about 15% by weight of alumina, and/or magnesia in the final catalyst, preferably-from about 2 to about 10% thereof.

' In order to obtain a final composite containing the desired proportion of metal oxide components, the theoretical proportion of the initial reactants which will yield the final composition is charged to the metathasis reaction mixture. "Utilizing ethyl ortho-silicate, for example, as thec'omponent of the metathasis reactionmixture capable of yielding the silica component of the ultimate catalystcornposite, 1 mole of the ethyl silicic acid esteror approximately 208 weight equivalents of the ester will yield 1 mole of silicon dioxide or approximately 60 weight equivalents thereof; Likewise, utilizing magnesium di-ace- "tate as the component'of the reaction mixture capable'of yielding the magnesia component of the ultimate catalyst composite, approximately 142,3 weight equivalents of the acetate will yield 1 mole of magnesia or approximately 40.3 weight equivalents thereof. It is not to be assumed,

however, that exact molar equivalents of the silica-yielding reactant and the'magnesiaor alumina-yielding reactants need necessarily "be employed in the metathasis reaction, since the reaction proceedsin the presence of a'mola'r excess of either reactant and the proportion thereof desired will ultimately depend upon the desired 'compositionof the catalyst composite.- j

The product of the initial metathasis reaction between the silica-yielding reactant and; the magnesia and/or alumina-yieldingreactant contains an excess of at least one of said reactants which, unless exact molar equivalents of said-reactants were utilized in the reaction, is usually present to some extent in the'product of the initial metathasis reaction. In order to convert this excess, ordinarily contained in the'initial product, to the corresponding metal oxide, the product of the initial reaction is subsequently heated to a somewhat higher temperature. preferably in the presence of water under high pres-*-'- sures to hydrolyze the unconverted reactant to the metal oxide orhydroxide. Since the excess reactant is. usually, the alkyl ortho-silicate (that is, to ultimatelyprepare a catalyst containing from about to about 99-1 of the silica component, ordinarily utilized in hydrocarbon cracking reactions) heating of the initial reaction mixture thus ordinarily effects decomposition or temperatures following the initial metathasis reaction. The above-referred to heating operation-or hydrolytic reaction is usually'efiected in aclosed system under pressure and at tempera- "tures of from about 150 to about 350"Cf'to substantially free the reaction residue of volatile matter. In case the desired reaction is-to be one of "hydrolysis, "water in "'sufiicient 1 quantity to "hydrolyze the "remaining ortho-silicate ester or "anyr'esidue of aluminum and/or magnesium organic acid" salt'is added to the reaction mixture and'hea-ted in the closedsystem at a superatmospheric' pressure. The organic residues combined in the excessofthe unconverted reactants are largely volatile and therefore-are released from the reaction mixture following the completion v "of thesecondary heating or hydrolytic reaction.

} (After completion 'ofthe secondary heating reaction, thepro'duct, usually a white, friable solid "mass, is'heated at a higher temperature to calcine thecomposite -and activate 1 the components for catalytic purposes. In the latter calcination, the

' reaction mass is heated'to' temperatures of from "aboutf15 'to about 800 C.,"usually in the presence of oxygen, such as a stream of air, which "oxidizesa'ny' or the remaining organic residue to volatile components, which"-are removed from "the catalyst 'reaction mixture and eliminated from the'final composite. The resulting product 'maybe ground to apowder and subsequently "pelleted into pills of desired size for use in hydro- "j'carbon conversion reactions or the original shape "of-'thefmass may be retained in its porous con- "dition'foruse in the reaction. The reaction periods allowed for each of thepreceding'reactionstepsis dependent upon the depth of conver'siondesiredin each instance. For example, the initial metathasis reaction is usually completed afterrea'ction periods of from about to ab'o'ut 4 hours, although in most instances, from 1 to 2 hours is sufficient. The subsequent heat treatment or hydrolytic conversion is usually completed within to about 3 hours, whereas the calcination stage of the process is desirably continuedfor areaction period of from about 2 to about 5* hours. The finished'catalyst composites "of the present invention'a re notably free of sodium' ionsand other-extraneous foreign impurities which often'have an adverse efiect on the catalytic activity and/or life of the catalyst compo'site. This is 'especiallytrue when care is taken to select pure reactants or charging "stocks, such as materials formed by subjecting the initial reactants to a purification treatment prior to the metathasis reaction. For example, a low grade aluminum oxide ore containing various extraneous impurities, such as iron, calcium, barium, etc. oxides or ions, may be substantially purified of said foreign impurities during the conversion of the alumina ore to the organic acid salt of aluminum. Thus, for example, in the preparation of basic aluminum acetate by the reaction of an alumina ore with acetic acid at the temperatures and pressures hereinbefore specified, very often water-soluble acetate salts of the impurities or salts which are soluble in the excess of the acid reagent are formed during the reaction which may be separated from-the basic aluminum acetate product. The subse- "quently' separated-basic aluminum acetate when charged to the present reaction form "composites-which containvery little, ifany, of the original impurities appearing in the alumina, "starting *material. art having a chemical composition somewhat Catalysts of the prior similar to catalysts of this invention, in many cases contain alkali metal ions introduced into the "composite during the preparationof -the catalyst viaprecipitation ofthe metal oxides'on "a silica gel through the addition of an alkali metal hydroxide "tofa suspension-jot :silica gel particles impregnated-with a salt of aluminum and/ormagnesium. "The catalysts of thisinven- *tion 'bein'g free of 'deactivating foreign components, have higher activities and"w'ithstand repeated regeneration more effectively than'has been observed in the case of even the bestof the catalysts of theprior' art.

The novel method of preparing silica-base "catalysts'by' the process herein provided through "ametathasis-type 'of 'reaction is essentially responsible for the unusually -low"density and high "porosity characteristicsof' the present composites. The subsequent calcinationof the" catalyst coinposite product, while in its highly porous state, results in the formation of 'a structurally' "rigid "catalyst particle, capable of withstanding consi'dera-blesurface pressure.

Theprocess of the present inventionis further illustrated in the following examples which are limited to'the preparation of specific catalysts and are not intended to define the scope of 'the invention in strict accordance thereto.

Basic aluminum acetate in the form of agranularwhite salt, insoluble in "water and formed by reacting 10 parts by'-=weight of anhydrous aluminala product of the Har'shaw Chemical Company) with 103 partsby-weight of glacial acetic acid'at'a temperature of 180C. and=at a pressure of ratmospheres of nitrogen'in arotating'autocla-ve for 6 hours, subsequently filtered pable of yieldingalumina in-accordance with the present process. A mixture of 40 weight proportio'ns (0.19-molar proportionslof ethyl -ortho-- silicate and '32 weightproportions (0.10 molar proportion) of the above basic aluminurn'acetam was heated at 200 for 6 hours in a rotating autoclave. The product, consisting of a white; hard solid and'a very slightly yellow liquid, weighed '69-weight proportions. The liquid portion of-thc "productreadilydistilled from the hard-white solid at suba'tmospheric pressure and re-distillation of theliquid'indicatd that it consisted of'a'mixture of ethyl etherandethyl acetate.

The: 39 weight proportions of white solidremaining after evaporation of the liquid product was heated in an oven at 200 C. for 3 hours, yielding a product weighing 32 weight proportions. The latter product heated in an air stream at approximately 550 C. for 2 hours yielded 20 grams of a hard white solid which was ground to pass through a 30- mesh screen.

The powdered solid prepared as in the above procedure and comprising a composite of alumina and silica was pressed into the shape of pills of approximately A" by 4" dimensions and utilized as the catalyst in a test to determine the ability of the composite to catalytically crack hydrocarbons. A Mid-Continent gas-oil fraction havfor a test period of approximately 2 hours. The

liquid hydrocarbon product boiling at a temperature above 400 F. was condensed in the receiver and the gaseous fraction, together with the gasoline product boiling at a temperature below about 400 F., was collected in a separate vessel. The

.weight per cent conversion, expressed as the total weight of 400 F. end point gasoline formed in the conversion and uncondensed gas divided by the weight of the oil charged and the result multiplied by 100 for the present catalyst was 24.2% on a once through basis.

Iclaim:

1. A process for the production of a catalyst composite comprising silica and at least one metal oxide selected from the group consisting of alumina and magnesia which comprises reacting an alkyl ortho-silicate with at least one organic acid metal salt selected from the group consisting of a monobasic aluminum organic acid salt and a magnesium organic acid salt at temperature of from about 150 to about 300 C. and under a pressure sufficient to maintain at least a portion of the reaction mixture in liquid phase, and calcining the resultant reaction product.

2.,A process for the production of a. catalyst composite comprising silica and at least one metal oxide selected fromthe group consisting of alumina and magnesia, which comprises reacting an allgyl ortho-silicate with at least one organic acid metal salt selected fromthe group consisting of a monobasic aluminum organic acid salt and a. magnesium organic acid salt at a temperature of from about 150 to about 300 C. and at a pressure sufficient to maintain at least a portion of the reaction mixture in liquid phase, and thereafter heating the resulting product in the presence of oxygen to calcine the solid residue and form said catalyst composite substantially free of organic material.

- 3. The process of claim 2 further characterized in that the reactionproduct is heated to a temperature of from about 500 to about 800 C.

4. A process for the production of a catalyst composite comprising silica and at least one metal oxide selected from the group consisting of alumina and magnesia, which comprises react- I ing an-alkyl'ortho-silicate with at least one organic acid metal salt selected from, the group consisting of a monobasic aluminum organic acid at a pressure sufiicient to maintain at least a portion of the reaction mixture in liquid phase,

heating the resulting product in the presence of water at a temperature of from about 150 to about 350 C. and at a superatmospheric pressure to hydrolyze unreacted components and thereafter calcining the recovered solid residue to form said catalyst composite substantially free of organic material.

5. A process for the productionof a catalyst composite comprising silica and alumina which comprises reacting an alkyl ortho-silicate with monobasic aluminum acetate at a temperature 'offfrom about 150 to about 300 C. and under a pressure sufllcient to maintain at least a portion of the reaction mixture in liquid phase and calcining the resultant reaction product.

'6.'A process for the pr'oductionof a catalyst composite comprising silica and magnesia which comprises reacting an alkyl ortho-silicate with 7 magnesium di-acetate at a temperature of from Number about to about 300 C. and under a pressure sufiicient'to maintain'at least a portion of the reaction mixture in liquid phase, and calcining the resultant reaction product.

7. A process for the production of a catalyst composite comprising silica and alumina. which comprises reacting ethyl ortho-silicate with monobasic aluminum acetate at a temperature of from about 150 to about 300 C and under a pressure sufiicient to maintain at least a portion of the reaction mixture in liquid phase, and calcining the resultant reaction product.

8. A process for the production of a catalyst composite of silica and alumina which comprises reacting ethyl ortho-silicate and nlonobasic alu 'm-inum acetate at a, reaction temperature of from about180 to about 250 C. and at a pressure sufficient to maintain the reactants in substantially liquid phase, thereafter adding water to the resulting residue and heating the mixture to a temperature of from about 150 to about 250 C., at a superatmospheric pressure to hydrolyze unreacted components, and calcining the recovered solid product at a temperature of from about 500 to about 800 C. to form said catalyst composite substantially free of organic material.

' JAMES P. WEST.

REFERENCES CITED The following references are of record in the me of this patent: r

UNITED STATES PATENTS I Name Date 7 2,348,647 Reeves et al. May 9, 1944 2,391,481 Ruthrufi Dec. 25, 1945 2,419,272 Marisic et a1. Apr. 22, 1947' Thomas Dec. 16,1947

' OTHER REFERENCES Journal American Chemical Society, vol. 50,

v pp. 3060-3061, NOV. 1928. (Copy in Lib) Wendie-see i 

1. A PROCESS FOR THE PRODUCTION OF A CATALYST COMPOSITE COMPRISING SILICA AND AT LEAST ONE METAL OXIDE SELECTED FROM THE GROUP CONSISTING OF ALUMINA AND MAGNESIA WHICH COMPRISES REACTING AN ALKYL ORTHO-SILICATE WITH AT LEAST ONE ORGANIC ACID METAL SALT SELECTED FROM THE GROUP CONSISTING OF A MONOBASIC ALUMINA ORGANIC ACID SALT AND A MAGNESIUM ORGANIC ACID SALT AT A TEMPERATURE OF FROM ABOUT 150* TO ABOUT 300* C. AND UNDER A PRESSURE SUFFICIENT TO MAINTAIN AT LEAST A PORTION OF THE REACTION MIXTURE IN LIQUID PHASE, AND CALCINING THE RESULTANT REACTION PRODUCT. 